Glucokinase (GK) is one of four exokinases that are found in mammals [Colowick, S. P., in The Enzymes, Vol. 9 (P. Boyer, ed.) Academic Press, New York, N.Y., pages 1-48, 1973]. The hexokinases catalyze the first step in the metabolism of glucose, i.e., the conversion of glucose to glucose-6-phosphate. Glucokinase has a limited cellular distribution, being found principally in pancreatic xcex2-cells and liver parenchymal cells. In addition, GK is a rate-controlling enzyme for glucose metabolism in these two cell types that are known to play critical roles in whole-body glucose homeostasis [Chipkin, S. R., Kelly, K. L., and Ruderman, N. B. in Joslin""s Diabetes (C. R. Khan and G. C. Wier, eds.), Lea and Febiger, Philadelphia, Pa., pages 97-115, 1994]. The concentration of glucose at which GK demonstrates half-maximal activity is approximately 8 mM. The other three hexokinases are saturated with glucose at much lower concentrations ( less than 1 mM). Therefore, the flux of glucose through the GK pathway rises as the concentration of glucose in the blood increases from fasting (5 mM) to postprandial (xcx9c10-15 mM) levels following a carbohydrate-containing meal [Printz, R. G., Magnuson, M. A., and Granner, D. K. in Ann. Rev. Nutrition Vol. 13 (R. E. Olson, D. M. Bier, and D. B. McCormick, eds.), Annual Review, Inc., Palo Alto, Calif., pages 463-496, 1993]. These findings contributed over a decade ago to the hypothesis that GK functions as a glucose sensor in xcex2-cells and hepatocytes (Meglasson, M. D. and Matschinsky, F. M. Amer. J. Physiol. 246, E1-E13, 1984). In recent years, studies in transgenic animals have confirmed that GK does indeed play a critical role in whole-body glucose homeostasis. Animals that do not express GK die within days of birth with severe diabetes while animals overexpressing GK have improved glucose tolerance (Grupe, A., Hultgren, B., Ryan, A. et al., Cell 83, 69-78, 1995; Ferrie, T., Riu, E., Bosch, F. et al., FASEB J., 10, 1213-1218, 1996). An increase in glucose exposure is coupled through GK in xcex2-cells to increased insulin secretion and in hepatocytes to increased glycogen deposition and perhaps decreased glucose production.
The finding that type II maturity-onset diabetes of the young (MODY-2) is caused by loss of function mutations in the GK gene suggests that GK also functions as a glucose sensor in humans (Liang, Y., Kesavan, P., Wang, L. et al., Biochem. J. 309, 167-173, 1995). Additional evidence supporting an important role for GK in the regulation of glucose metabolism in humans was provided by the identification of patients that express a mutant form of GK with increased enzymatic activity. These patients exhibit a fasting hypoglycemia associated with an inappropriately elevated level of plasma insulin (Glaser, B., Kesavan, P., Heyman, M. et al., New England J. Med. 338, 226-230, 1998). While mutations of the GK gene are not found in the majority of patients with type II diabetes, compounds that activate GK and, thereby, increase the sensitivity of the GK sensor system will still be useful in the treatment of the hyperglycemia characteristic of all type II diabetes. Glucokinase activators will increase the flux of glucose metabolism in xcex2-cells and hepatocytes, which will be coupled to increased insulin secretion. Such agents would be useful for treating type II diabetes.
This invention provides a compound comprising an amide of the formula:

wherein
A is unsubstituted phenyl or phenyl which is mono- or di-substituted with halo or mono-substituted with lower alkyl sulfonyl, lower alkyl thio or nitro; p1 R1 is cycloalkyl having from 3 to 9 carbon atoms or lower alkyl having from 2 to 4 carbon atoms;
R2 is an unsubstituted or mono-substituted five- or six-membered heteroaromatic ring connected by a ring carbon atom to the amine group shown, which five- or six-membered heteroaromatic ring contains from 1 to 3 heteroatoms selected from sulfur, oxygen or nitrogen, with one heteroatom being nitrogen which is adjacent to the connecting ring carbon atom, which ring may be monocyclic or fused with phenyl at two of its ring carbons, said monosubstituted heteroaromatic ring being monosubstituted at a position on a ring carbon atom other than adjacent to said connecting carbon atom with a substituent selected from the group consisting of halo, lower alkyl, nitro, cyano, perfluoro-lower alkyl; hydroxy, xe2x80x94(CH2)nxe2x80x94OR3, xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94OR3, xe2x80x94(CH2)nxe2x80x94C(O)xe2x80x94NHxe2x80x94R3, xe2x80x94C(O)C(O)xe2x80x94OR3, or xe2x80x94(CH2)nxe2x80x94NHR3; where R3 is hydrogen or lower alkyl; and n is 0, 1, 2, 3 or 4; or a pharmaceutically acceptable salts or N-oxides thereof.
Preferably R2 is a five- or six-membered heteroaromatic ring connected by a ring carbon atom to the amine group shown in formula I, which five- or six-membered heteroaromatic ring contains from 1 to 3 heteroatoms selected from sulfur, oxygen or nitrogen, with one heteroatom being nitrogen which is adjacent to the connecting ring carbon atom. This ring may be monocyclic or may be fused with phenyl at two of its ring carbons. In accordance with an embodiment of this invention, the adjacent nitrogen in the nitrogen containing heteroaromatic rings may be in the form of an N-oxide where the nitrogen adjacent to the ring carbon atom is converted to an N-oxide. On the other hand, compounds of formula I can be in the form of pharmaceutically acceptable salts.
The compounds of formula I have been found to activate glucokinase in vitro. Glucokinase activators are useful for increasing insulin secretion in the treatment of type II diabetes.
This invention provides a compound comprising an amide of the formula I above or a pharmaceutically acceptable salt thereof.
In the compound of formula I, the xe2x80x9c.xe2x80x9d illustrates the asymmetric carbon atom in this compound. The compound of formula I may be present as a racemate at the asymmetric carbon shown. However, the xe2x80x9cSxe2x80x9d enantiomers, where the amide is in the xe2x80x9cSxe2x80x9d configuration at the asymmetric carbon, is preferred. When the phenyl ring A is monosubstituted with lower alkyl sulfonyl, nitro or lower alkyl thio, it is preferred that it is substituted at the 5- or 6-position as indicated in formula I. Thus, when A is phenyl substituted with nitro, it is preferred that this substitution be at positions 5 or 6 such as 5-nitro phenyl and 6 nitro phenyl.
In one embodiment of formula I, the R2 ring as described above is a single, or monocyclic (unfused) ring. When R2 is a monocyclic ring, it is preferably substituted or unsubstituted pyridine. In another embodiment of formula I, the R2 ring as described above is a bicyclic ring, i.e. is fused with a phenyl.
As used throughout this application, the term xe2x80x9clower alkylxe2x80x9d includes both straight chain and branched chain alkyl groups having from 1 to 10 and preferably 3 to 9 carbon atoms, such as propyl, isopropyl, heptyl, and especially 2 to 4 carbon atoms.
As used herein, the term xe2x80x9ccycloalkylxe2x80x9d signifies a 3- to 9-membered cycloalkyl ring, preferably 5- to 8-membered, for example cyclopentyl, cyclohexyl, cycloheptyl, or cyclooctyl.
As used herein, xe2x80x9cperfluoro-lower alkylxe2x80x9d means any lower alkyl group wherein all of the hydrogens of the lower alkyl group are substituted or replaced by fluoro. Among the preferred perfluoro-lower alkyl groups are trifluoromethyl, pentafluoroethyl, heptafluoropropyl, etc.
As used herein, xe2x80x9clower alkyl thioxe2x80x9d means a lower alkyl group as defined above bound to the rest of the molecule through the sulfur atom in a thio group.
As used herein, xe2x80x9clower alkyl sulfonylxe2x80x9d means a lower alkyl group as defined above bound to the rest of the molecule through the sulfur atom in a sulfonyl group.
As used herein, the term xe2x80x9chalogenxe2x80x9d is used interchangeably with the word xe2x80x9chaloxe2x80x9d, and, unless otherwise stated, designates all four halogens, i.e. fluorine, chlorine, bromine, and iodine.
As used herein, the term xe2x80x9cN-oxidexe2x80x9d means a negatively charged oxygen atom which is covalently linked to a nitrogen which is positively charged in a heteroaromatic ring.
As used herein, xe2x80x9cheteroaromatic ringxe2x80x9d means a five or six membered unsaturated carbacyclic ring where one or more carbon is replaced by a heteroatom such as oxygen, nitrogen, or sulfur. The heteroaromatic ring may be a single cycle or may be bicyclic, i.e. formed by the fusion of two rings.
The heteroaromatic ring defined by R2 can be an unsubstituted or mono-substituted five- or six-membered heteroaromatic ring having from 1 to 3 heteroatoms selected from the group consisting of oxygen, nitrogen, or sulfur and connected by a ring carbon to the amine of the amide group shown. At least one heteroatom is nitrogen and is adjacent to the connecting ring carbon atom. If present, the other heteroatoms can be sulfur, oxygen or nitrogen. The ring defined by R2 may be a single cycle. Such heteroaromatic rings include, for example, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, isoxazolyl, isothiazolyl, pyrazolyl, thiazolyl, oxazolyl, and imidazolyl. A preferred heteroaromatic ring is pyridinyl. The ring defined by R2 may be a bicyclic, i.e. may be fused with phenyl at two of its free ring carbons. Examples of such rings are benzimidazolyl, benzothiazolyl, quinolynyl, benzooxazolyl, and so forth. The ring defined by R2 is connected via a ring carbon atom to the amide group to form the amides of formula I. The ring carbon atom of the heteroaromatic ring which is connected via the amide linkage to form the compound of formula I cannot contain any substituent. When R2 is an unsubstituted or mono-substituted five-membered heteroaromatic ring, the preferred rings are those which contain a nitrogen heteroatom adjacent to the connecting ring carbon and a second heteroatom adjacent to the connecting ring carbon.
As used herein, xe2x80x94C(O)OR3 represents

and so forth.
The term xe2x80x9cpharmaceutically acceptable saltsxe2x80x9d as used herein include any salt with both inorganic or organic pharmaceutically acceptable acids such as hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, phosphoric acid, citric acid, formic acid, maleic acid, acetic acid, succinic acid, tartaric acid, methanesulfonic acid, paratoluene sulfonic acid and the like. The term xe2x80x9cpharmaceutically acceptable saltsxe2x80x9d also includes any pharmaceutically acceptable base salt such as amine salts, trialkyl amine salts and the like. Such salts can be formed quite readily by those skilled in the art using standard techniques.
Also part of this invention are prodrugs of the compound of formula I. By prodrug is meant a metabolic precursor of a drug which when administered to a patient breaks down into the drug and acceptable by-products. Compounds of this invention may be made into any conventional prodrug. One particular prodrug of this invention are the N-oxides as described above. Any individual compound of this invention may be obtained as a prodrug in general.
During the course of the reactions provided below in the Reaction Scheme and discussion, the various functional groups such as the free carboxylic acid or hydroxy groups may be protected via conventional hydrolyzable ester or ether protecting groups. As used herein, the term xe2x80x9chydrolyzable ester or ether protecting groupsxe2x80x9d designates any ester or ether conventionally used for protecting carboxylic acids or alcohols which can be hydrolyzed to yield the respective carboxyl or hydroxyl group. Exemplary ester groups useful for those purposes are those in which the acyl moieties are derived from a lower alkanoic, aryl lower alkanoic, or lower alkane dicarboxylic acid. Among the activated acids which can be utilized to form such groups are acid anhydrides, acid halides, preferably acid chlorides or acid bromides derived from aryl or lower alkanoic acids. Examples of anhydrides are anhydrides derived from monocarboxylic acid such as acetic anhydride, benzoic acid anhydride, and lower alkane dicarboxylic acid anhydrides, e.g. succinic anhydride as well as chloro formates e.g. trichloro, ethylchloro formate being preferred. A suitable ether protecting group for alcohols are, for example, the tetrahydropyranyl ethers such as 4-methoxy-5,6-dihydroxy-2H-pyranyl ethers. Others are aroylmethylethers such as benzyl, benzhydryl or trityl ethers or xcex1-lower alkoxy lower alkyl ethers, for example, methoxymethyl or allylic ethers or alkyl silylethers such as trimethylsilylether.
Similarly, the term xe2x80x9camino protecting groupxe2x80x9d designates any conventional amino protecting group which can be cleaved to yield the free amino group. The preferred protecting groups are the conventional amino protecting groups utilized in peptide synthesis. Especially preferred are those amino protecting groups which are cleavable under mildly acidic conditions from about pH 2 to 3. Particularly preferred amino protecting groups are t-butyl carbamate (BOC), benzyl carbamate (CBZ), and 9-fluorenylmethyl carbamate (FMOC).
In a preferred compound of formula I, R1 is cycloalkyl having from 5 to 8 carbon atoms, and R2 is an unsubstituted or mono-substituted five- or six-membered heteroaromatic ring connected by a ring carbon atom to the amine group shown, which five- or six-membered heteroaromatic ring contains from 1 to 2 heteroatoms selected from sulfur, oxygen or nitrogen, with one heteroatom being nitrogen which is adjacent to the connecting ring carbon atom, which ring may be a single cycle, or may be fused with a phenyl at two of its ring carbons, said mono-substituted heteroaromatic ring being monosubstituted at a position on a ring carbon atom other than adjacent to said connecting carbon atom with a substituent selected from the group consisting of halo or lower alkyl (Formula AB). R2 as described in Formula AB may be a monocyclic ring (Formula A), or may be a bicyclic ring through fusion with phenyl (Formula B). In compounds of formula A, it is particularly preferred that R2 is substituted or unsubstituted pyridine. It is also preferred that R1 is cyclohexyl. Phenyl A is preferably unsubstituted.
In a preferred compound of Formula I, R1 is cyclohexyl and R2 is a monocyclic ring (Formula A-1). It is preferred in compounds of Formula A-1 that phenyl A is unsubstituted. It is particularly preferred that R2 is substituted or unsubstituted pyridine.
In one embodiment of Formula A-1, R2 is unsubstituted pyridine, and in another R2 is a mono-substituted pyridine. Preferably, the substituent is halo such as bromo, fluoro or chloro or lower alkyl such as methyl.
In one embodiment of Formula A-1, R2 is a mono-substituted pyrimidine. Preferably, the substituent is lower alkyl, such as methyl, and phenyl A is unsubstituted. R2 may also be an unsubstituted pyrimidine of Formula A-1. Preferably, phenyl A is unsubstituted or substituted with lower alkyl sulfonyl at the 4 or 7 position.
In one embodiment of Formula A-1, R2 is unsubstituted thiazole. In preferred such compounds, A is phenyl unsubstituted, or substituted with chloro at positions 5 and 6, or substituted with nitro at positions 5 or 6, or substituted with halo or lower alkyl sulfonyl at positions 4 or 7.
In one embodiment of Formula A-1, R2 is a mono-substituted thiazole. Preferably, the substituent is halo, and A is phenyl unsubstituted, or substituted with chloro at positions 5 and 6, or substituted with nitro at positions 5 or 6, or substituted with halo or lower alkyl sulfonyl at positions 4 or 7.
In one embodiment of Formula A-1, R2 is an unsubstituted pyrazine. A is preferably phenyl unsubstituted, or substituted with halo or lower alkyl sulfonyl at positions 4 or 7.
In one embodiment of Formula A-1 where R1 is cylohexyl and R2 is a monocyclic ring, R2 is unsubstituted imidazole, and phenyl and A is preferably unsubstituted phenyl.
In another embodiment of Formula I or of Formula A, phenyl A is unsubstituted, R2 is a monocyclic ring, and it is preferable that R2 is substituted or unsubstituted thiazole. (Formula A-2). In some compounds of Formula A-2, R1 is cyclopentyl, in others, R1 is cycloheptyl, and in others, R1 is cyclooctyl.
In a preferred compound of Formula I where R2 is a bicyclic heteroaromatic ring through fusion with phenyl at two of its ring carbons and R1 is cyclohexyl (Formula B-1). In compounds of Formula B-1, it is preferred that phenyl A is unsubstituted. It is further preferred that R2 is benzthiazole, benzimidazole, benzoxazole, or quinoline, all preferably unsubstituted.
The compounds of this invention can be prepared by the following Reaction Schemes where phenyl A, R1, R2, and R3 are as in formula I.



The compounds of this invention may be obtained by reacting substituted ortho-phenylene dialdehyde 1 or 1xe2x80x2, with amino acid derivative 2 or 2xe2x80x2 in a suitable solvent such as acetonitrile, to obtain carboxylic acid derivative 3 or 3xe2x80x2. 3 or 3xe2x80x2 may then be coupled with a suitable heteroaromatic amine H2Nxe2x80x94R2 under conventional reaction conditions for amide bond formation to obtain the compounds of formula I.
Compounds of formula I where phenyl A is substituted with halo (obtained from a halo phthalic acid) or nitro are obtained as described in Scheme 2 above where 4 is a suitable commercially available substituted phthalic acid. The substituted ortho-phenylene dialdehydes 1 or 1xe2x80x2 may be prepared by reduction of the phthalic acids 4 to the diol intermediates followed by oxidation to provide 1xe2x80x2.
Compounds of formula I where phenyl A is substituted with lower alkyl sulfonyl may be prepared starting from a phthalic acid 4 where Ra is fluoro and Rb is hydrogen by a multistep sequence:
a) conversion to the corresponding dimethyl ester with sulfuric acid in methanol
b) nucleophilic displacement of fluoride with with sodium thiomethoxide in a suitable solvent such as dimethylsulfoxide to provide 4 when Ra is lower alkyl thio,
c) reduction of the resulting phthalic acid 4 when Ra is lower alkyl thio to the diols followed by oxidation to the corresponding ortho-phenylene dialdehyde 1 when Ra is lower alkyl thio
d) reaction of the ortho-phenylene dialdehyde 1 when Ra is lower alkyl thio an amino acid 2 in refluxing acetonitrile to give a mixture of the lower alkyl thio, lower alkyl thio carboxylic acid isomers 3 and
e) coupling with H2Nxe2x80x94R2 to provide compounds of formula I where Ra is lower alkyl thio.
Compounds of formula I where Ra is lower alkyl sulfonyl and Rb is hydrogen, can be obtained by first oxidizing the lower alkyl isomers of step (d) above with hydrogen peroxide to form the lower alkyl sulfonyl carboxylic acid of formula 3 (Ra is lower alkyl sulfonyl, Rb is hydrogen and then coupling the resulting carboxylic acid of formula 3 with H2Nxe2x80x94R2 to provide the compound of formula I where Ra is lower alkyl sulfonyl.
Compounds of formula I where R1 is C3-C9 cycloalkyl or C2-C4 alkyl (in R, S, or racemic form) are obtained as described above where 2 or 2xe2x80x2 is a suitable commercially available amino acid. Amino acid 2 or 2xe2x80x2 may also be obtained according to Scheme 3 from 5. 5 is prepared according to the literature procedure (see O""Donnell, M. J.; Polt, R. L. J. Org. Chem. 1982, 47, 2663-2666) and may be reacted under basic conditions with a suitable alkyl halide reagent substituted with the desired R1 to obtain, after acidic hydrolysis, any amino acid 2. The alkyl halide reagent may be obtained commercially or made using conventional methods.
Compounds of formula I where R2 is as described in formula I may be obtained by coupling the desired heteroaromatic amine (which is commercially available or can be made by conventional methods) to carboxylic acid derivative 3 or 3xe2x80x2 under conventional conditions for reacting an amine with an acid. For compounds of Formula II, the N-oxide heteroaromatic amine (for example 2-aminopyridine-N-oxide) may be coupled to 3 or 3xe2x80x2, or the corresponding compound of Formula I may be oxidized at an unsubstituted R2 ring by known methods to obtain an N-oxide.
If it is desired to produce the R or the S isomer of the compound of formula I, this compound can be separated into these isomers by conventional physical or chemical means. One physical means of separation involves resolution of the enantiomeric pairs of compounds of formula I using a high performance liquid chromatography instrument equiped with a chromatographic column loaded with a chiral agent. Among the preferred chemical means is to react the intermediate carboxylic acid 3 or 3xe2x80x2 with an optically active base. Any conventional optically active base can be utilized to carry out this resolution. Among the preferred optically active bases are the optically active amine bases such as alpha-methylbenzylamine, quinine, dehydroabietylamine and alpha-methylnaphthylamine. Any of the conventional techniques utilized in resolving organic acids with optically active organic amine bases can be utilized in carrying out this reaction.
In the resolution step, 3 or 3xe2x80x2 is reacted with the optically active base in an inert organic solvent medium to produce salts of the optically active amine with both the R and S isomers of 3 or 3xe2x80x2. In the formation of these salts, temperatures and pressure are not critical and the salt formation can take place at room temperature and atmospheric pressure. The R and S salts can be separated by any conventional method such as fractional crystallization. After crystallization, each of the salts can be converted to the respective 3 or 3xe2x80x2 in the R and S configuration by hydrolysis with an acid. Among the preferred acids are dilute aqueous acids , i.e., from about 0.001N to 2N aqueous acids, such as aqueous sulfuric or aqueous hydrochloric acid. The configuration of 3 or 3xe2x80x2 which is produced by this method of resolution is carried through the entire reaction scheme to produce the desired R or S isomer of formula I or II. The separation of R and S isomers can also be achieved using an enzymatic ester hydrolysis of any lower alkyl ester derivatives of 3 or 3xe2x80x2 (see for example, Ahmar, M.; Girard, C.; Block, R, Tetrahedron Lett, 1989, 7053), which results in the formation of corresponding chiral acid and chiral ester. The ester and the acid can be separated by any conventional method of separating an acid from an ester. Another preferred method of resolution of racemates of the compounds 3 or 3xe2x80x2 is via the formation of corresponding diastereomeric esters or amides. These diastereomeric esters or amides can be prepared by coupling the carboxylic acids 3 or 3xe2x80x2 with a chiral alcohol or a chiral amine. This reaction can be carried out using any conventional method of coupling a carboxylic acid with an alcohol or an amine. The corresponding diastereomers of the derivatives of carboxylic acids 3 or 3xe2x80x2 can then be separated using any conventional separation methods, such as HPLC. The resulting pure diastereomeric esters or amides can then be hydrolyzed to yield the corresponding pure R or S isomers. The hydrolysis reaction can be carried out using conventional known methods to hydrolyze an ester or an amide without racemization.